Open structure polishing pad and methods for limiting pore depth

ABSTRACT

An improved polishing pad, starting from a traditional sintered pad core or similar, is designed with a feature that controls the pore depth of the polishing pad. The pad interstitials are impregnated with a chosen material. This material is then liberated from the surface of the pad, by a variety of methods, leaving the remaining void space to form the desired surface texture for polishing. The invention allows for the bulk properties of the pad to remain more solid-like with a higher modules for improved planarization. At the same time a surface porosity depth is limited to both create an ideal surface texture and to allow for the polishing pad surface to remain clean and free of polishing by products and debris that tend to build-up with in the depths of a traditional sintered pad. This invention yields a polishing pad that is better suited for applications such as semiconductor wafer polishing, and the like.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is entitled to the benefit of Provisional PatentApplication Ser. No. 60/262947, dated Jan. 19, 2001.

BACKGROUND—FIELD OF THE INVENTION

[0002] This patent relates to the art of polishing pads, including butnot limited to the polishing of silicon wafers, semiconductor wafers,patterned packaging and circuit boards, compound semiconductors, gemstones and the like.

BACKGROUND: PRIOR ART

[0003] Prior art teaches that polishing pads need surface texture (ortopography) to effectively polish semiconductor wafers and the like.Several methods have been used to create such texture as cited in U.S.Pat. No. 5,489,233 including:

[0004] 1. Urethane Impregnated polyester felts (examples in U.S. Pat.No. 4,927,432) possess a micro texture derived from the ends ofprojecting fibers within the bulk composite, together with associatedvoids.

[0005] 2. Micro-porous urethane pads of the type sold as Politex byRodel, Inc. of Newark Del. have a surface texture derived from the endsof columnar void structures within the bulk of a urethane film which isgrown on a urethane felt base.

[0006] 3. Filled and/or blown composite urethanes such as IC-series,Mh-series and LP-series polishing pads manufactured by Rodel, Inc. ofNewark Del. have a surface structure made up of semicircular depressionsderived from the cross-section of exposed hallow spherical elements orincorporated gas bubbles.

[0007] 4. Abrasive-filled polymeric pads such as those of U.S. Pat. No.5,209,760 possess a characteristic surface texture consisting ofprojections and recesses where filler grains are present or absent.

[0008] In addition to these referenced methods, other methods ofproviding surface texture have been cited and patented.

[0009] 5. Sintering polymeric particles (U.S. Pat. No. 6,017,265), wherethe micro-texture is derived from the pre-sintered particles, gapsbetween particles and fused polymeric-particle-sections.

[0010] 6. Mechanically creating micro-texture via such methods asdiamond pad conditioning (U.S. Pat. No. 5,489,233).

[0011] Upon review, in all of these cases, successful pads for polishingsemiconductor wafer and the like utilize at least 2 of 3 key levels ofpad texturing:

[0012] I. Macro texturing, such as pad grooving, which is on the scaleof millimeters. This texture is usually formed by mechanical means, suchas using a metallic cutting tools or some form of patterned molding.

[0013] II. Intermediate scale—on the size scale of 5 to 250 microns(micro-meters=μm), usually in the form of a closed or an open porestructure.

[0014] III. Micro-texture—on the scale of less than 5 microns, usually2-3 microns. Micro-texture often is created with diamond conditioningmethods.

[0015] The six above mentioned pad types create the necessary texturingfor polishing all by different and distinct methods. Of these six padtypes, only methods 3, 4, 5 and 6 have been used effectively for theplanarization of semiconductor wafers and the like. Method 4 isunconventional in that abrasive in the pad is used to polish thework-piece, and will not be considered as a “standard” polishing pad forthis background discussion.

[0016] Of the remaining methods, 3, 4, 5 and 6, method 3 is usedpredominantly in the market place, in the form of the IC-1000 productline from Rodel Incorporated of Delaware. Shortcomings in the padsproduced by methods 5 and 6 have thus far limited their utility in themarket place.

[0017] Pads made by method 5 show some improvements for certainapplications over the IC-1000 pad made by method 3. As referenced inU.S. Pat. Nos. 6,017,265, 6,062,968 and, 6,126,532, more stable ratescan be achieved under certain polishing conditions. Pads made by method5 can be very effective for applications where a polishing-fluid richenvironment is desirable, as often found in more “chemical polishes”such as copper and tungsten polishing with some peroxide basedcommercially available slurries. In referring to the overall padstructures shown in U.S. Pat. Nos. 6,017,265, 6,062,968 and 6,126,532(also shown schematically in FIG. 5), continuous void spaces can beformed by the design of this pad. This network of attached void spaces(item 14 in FIG. 4) can act to float the polishing work-piece on areservoir of polishing fluid. In some polishing applications, a generousfluid reservoir is desirable, as compared to the IC-1000 pad. Inpractice however, the benefits of this reservoir are soon out weighed bydisadvantages. This continuous network of pores becomes filled with morethan the desired polishing fluid: polishing by-products, spent polishingfluid, rinse water, and pad conditioning by-products, as examples. Insome instances, the cycling of particle containing slurries andwork-piece rinsing fluids, can lead to agglomerated slurry particlesstuck in the deep network of pad pores. The formation of a very thinpolishing pad is impractical because the pad will not be thick enough toprovide the needed rigidity for polishing planarization and thick enoughto have a suitable life-time when coupled with standard diamond padcondition methods and the typical pad wear encountered in most polishingapplications.

[0018] This invention teaches new methods of forming and using polishingpads made by a method similar to those of method 5 above, but that forma controllable pore network depth into the polishing pad. In doing so,the polishing pads take full advantages of the performance potentialseen in method 5 pads, with out the undesirable characteristicsencountered with this deep and continuous pore network, as discussedabove. In addition to these advantages, this invention teaches that thenew pad design formed with achieve superior planarization and in somecases a longer polishing pad lifetime for applications such assemiconductor wafer polishing and the like.

SUMMARY

[0019] A polishing pad is formed consisting of a mixture of at least twodistinct material phases. The first phase is the network of polymerparticles, that may or may not be coalesced or sintered into a polishingpad matrix. The second phase consist of materials that occupy the voidspaces or gaps with in the first phase. This said second phase isliberated from the pad when in contact with the pad surface, by avariety of methods. The void spaces, once occupied by the second phaseof material, forms the said connected network of pores that forms theneeded surface texture for polishing. This invention offers a unique wayof forming a solid polishing pad and simultaneously forming acontrollable and reproducible surface-pore-depth.

DRAWINGS

[0020]FIG. 1 is a schematic microscopic cross sectional and surface viewof an article (polishing pad), in accordance to the present invention,after manufacture.

[0021]FIG. 2 is a higher magnification schematic microscopic crosssectional and surface view of an article (polishing pad), in accordanceto the present invention, as shown in FIG. 1.

[0022]FIG. 3 is a schematic microscopic cross sectional and surface viewof an article (polishing pad), in accordance to the present invention,after a surface pore or surface texture has been formed from thestructure shown initially in FIG. 1.

[0023]FIG. 4 is a higher magnification schematic microscopic crosssectional and surface view of an article (polishing pad), in accordanceto the present invention, as shown in FIG. 3.

[0024]FIG. 5 is a schematic microscopic cross sectional and surface viewof an article (polishing pad), in accordance to he current art.

[0025]FIG. 6 is a schematic microscopic cross sectional and surface viewof an article (polishing pad), in accordance to an embodiment of thepresent invention, as manufactured.

[0026]FIG. 7 is a high magnification schematic microscopic crosssectional and surface view of an article (polishing pad), in accordanceto the invention embodiment shown in FIG. 6, after the surface pore orsurface texture has been formed from the structure shown initially inFIG. 6.

[0027]FIG. 8 is a still higher magnification schematic microscopic crosssectional and surface view of the near surface region of the article(polishing pad), in accordance to the invention embodiment shown in FIG.7.

[0028]FIG. 9 is a high magnification schematic microscopic crosssectional and surface view of an article (polishing pad), in accordanceto an additional embodiment of the present invention, after the creationof surface pores or surface texture.

[0029]FIG. 10 is a schematic cross sectional and surface view of anarticle (polishing pad), during a diamond pad-conditioning treatment.

[0030]FIG. 11 is two schematic microscopic top surface views of the twopolishing pad material phases (as shown in FIG. 7), in accord with thisinvention, after current-art diamond pad conditioning on (a) solidmaterial phase 1 and (b) on the fill material (for some embodiments ofthe present invention), showing the conceptual design of the surfacemicro-texture.

[0031]FIG. 12 is a schematic cross sectional surface view of an article(polishing pad), in accordance to the present invention, with theaddition of macro-texturing groove cuts (the view does not include thedetail shown in earlier figures).

[0032]FIG. 13 is a schematic top surface view of an article (entirepolishing pad), in accordance to the present invention, showing theconceptual design of concentric circular grooving which is used tocreate surface macro-texturing of a polishing pad.

DESCRIPTION OF THE INVENTION

[0033] Referring to the drawings, wherein like numerals indicate likeelements throughout, there is shown in FIGS. 1-4, 6-13 embodiments of anarticle of manufacture, generally designated 100, 200, 400, 500, 600,and 800 in accordance with the present invention.

[0034] Preferably, the articles 100, 200, 400, 500, 600, and 800 aregenerally circular sheets or polishing pads, as best shown in FIG. 13(600). One of ordinary skill in the art would understand that the pad600, may for example be square, rectangular, in long sheets or belts orany desired suitable shape.

[0035] The article 200 et seq. of the present invention may be used as apolishing pad either by itself or as a substrate in a polishingoperation in which a polishing fluid is used to provide a desiredsurface finish for semiconductor devices, silicon devices, crystals,gases, ceramic, polymeric plastic material, metal stone or the like.Polishing pads 600 made with the article 200 et seq. of the presentinvention may be used with lubricants, coolants, and various abrasiveand non-abrasive polishing slurries, all well known to those skilled inthe art and readily available commercially.

[0036] In reference to FIG. 1 and FIG. 2, the said invention-polishingpad, article 100, is formed with a mixture of at least two distinctmaterial phases. The first phase is a collection of polymer particles11, that may or may not be coalesced or sintered into a polishing padmatrix. Henceforth, this phase may be referred to as the PPP, forpolymer particle phase. When these said particles are coalesced orsintered together, this said collection forms a single networkedstructure. Henceforth, network will be referred to as the PPM phase, forpolymer particle matrix phase. In FIG. 1, the said polymers particle(PPP) 11 are sintered to form such a network 11 (PPM). The second phase12 consist of materials that occupy the void spaces or gaps with thefirst phase. This occupancy of space need not be 100%. In FIG. 1, themore darkly shaded areas that fill the gaps between the coalescedparticles 11 represent this second phase continuous phase 12. Henceforth, this fill material will be referred to as the pore-depth-limitingphase or PDL. In FIG. 1 and all figures in their application, the upperportion of each drawing is intended to represent the topside or surfaceof the article (polishing pad). The remaining 3 sides of the as drawnarticles are assumed to run continuously and repeated in to the bulk ofthe said invented article, taking the macroscopic shape of the polishingpad as described above. As an exception, FIG. 13 represents a fullpolishing pad 600.

[0037] In reference to FIG. 3 and FIG. 4, the said second phase 12 hasbecome recessed below the initial polishing pad surface, as an operatingfeature of this invention. In accord with this invention, the saidsecond phase 12 (PDL) is liberated from the pad when in contact with thepad surface, by a variety of methods. These methods will be discussedlater in the invention description. The area once occupied by PDLmaterial 12 has become the newly created surface port layer 13. As thePDL material 12 are liberated, the newly created surface void spaces 14forms an interconnected network of pores that forms the needed surfacetexture for polishing. The rate at which the PDL phase 12 is liberatedfrom the surface is controlled by method of liberation, the materialschosen, the method of manufacture of the polishing pad and the operationof the polishing pad. In the preferred embodiment illustrated by FIG. 2,the said second phase material 12 is liberated by the surface by slowlychemically dissolving into the pad conditioning, rinsing or polishingfluids. The desired dissolution rate is first characterized by thematerial choice for the said PDL phase 12. In the preferred embodiment,the PDL phase 12 is a water-soluble polymer, such as from the Polyoxyseries from Union Carbide of Danbury Conn. In this case the rate ofdissolution is controlled by the molecular weight of the Polyoxy chosen,as described in the company literature. The material is chosen, in thepreferred case, so that the dissolution rate is approximately equal tothe net wear of the pad by both polishing and pad conditioningoperation. An initial pad rinsing pre-treatment can be used to set thepore depth 13 by this design (See FIGS. 3 and 4).

[0038]FIG. 5 shows the current art, which uses a single-phase 81polishing pad and calls for the surface and interstitial voids spaces 14to remain empty. These void spaces 14 become traps for unwantedpolishing pad conditioning and reaction by-products. In FIGS. 1-4, thesecond phase material acts to block this migration of by-products intothe pad interior, by limiting the depth that the void spaces 14penetrate into the bulk of the polishing pad 200. As a result, theseby-products remain on the surface and are easily rinsed away if sodesired. In addition, the liberation of the PDL phase 12, acts toundercut and release the by-products that deposit on the surface of PDLphase 12.

[0039] In reference to FIG. 6 and FIG. 7, as another embodiment of thisinvention, a different family of second phase materials (PDL-2) is used.Henceforth, these materials will be referred to as PDL-2 forpore-depth-limiting, version-2. This PDL-2 is not entirely liberatedfrom the pad surface. As shown in FIG. 6 and FIG. 7, the second phase ispartially liberated from the surface, leaving a series of interconnectedor distinct pores with in the interstitials of the particle phase 11. Inthis embodiment, the remaining material 23, may either wear at the samerate as the particle phase 11, leaving a nearly co-planar surface or thesaid remaining material 23 may also be liberated from the surface of thepad by any variety of methods, including a still slower rate ofdissolution relative to pore creating material in 22 (creating the pores26 shown in FIG. 8) or from a faster rate of mechanical wear than thatof the polymer particle phase 11.

[0040]FIG. 8 provides and exploded view of the said PDL-2 phase shown inFIG. 7. Shown are the void spaces 26 which are created when material wasliberated from the polishing pad surface (from material 22) as well asthe remaining second phase material 23. The said pore 26 sizes, volumeand shape are controlled by the method of manufacture, materials chosen,and operation of this invention embodiment, as will be discussed laterin the description of this invention.

[0041] As yet another separate embodiment of this invention, asillustrated in FIG. 9, the particle phase 11 of the polishing pad neednot be sintered or coalesced into a single network of material to beeffective. In this embodiment, the cohesive force of the polishing padmay also be provided by the second phase material, indicated here asphase 35. Henceforth, this third family of second phase materials willbe referred to as the PDL-3 for pore-depth-limiting phase, version 3. Asin the previous embodiments, this PDL-3 35 can be liberated from thesaid polishing pad material by a variety of methods, either in whole orin part. The preferred method for this embodiment is for the PDL-3material 35 to partially liberate from the surface by dissolution. Theremaining material 36 is then worn from the surface at the same rate toa slightly higher rate than the particle phase 11. In this version ofthis embodiment, the particle phase 11 is held with sufficient cohesiveforce to allow for the PPP particles to wear from the surface of the padrather than becoming torn or chipped out the pad surface. The cohesiveforce with in the PDL-3 and between the PDL-3 and the PPP can bealtered, by one skilled in the art, to control the release of said PPPparticles 11 from the surface during either the polishing, padconditioning or similar operation, if so desired.

[0042] For all embodiments of this invention, the creation of surfacemicro-texture is desirable. One method of creating this saidmicro-texture is by diamond pad conditioning. In some embodiments theparticle phase has no intrinsic surface texture. Diamond padconditioning can be used to create surface topography as illustrated inFIG. 10. FIG. 11 shows the surface structures formed by the currentdiamond pad conditioning art (FIG. 11a) on the particle phase 11. FIG.11b shows the said intrinsic surface texture of this invention in thePDL-2 23 and some embodiments of PDL-3 36. Diamond particle scratches 45and wakes 47, criss-cross the polymer particle surface 11, in a randomfashion. As these scratches 45 pass over one and another, micro texturetopography is created. In some cases the intrinsic surface porosity ofPDL-2 (and sometimes PDL-3) yields a closed cell pore. This closed cellsurface structure acts to hold the polishing fluid without escape,during the polishing operation, forming and maintaining a goodfluid-pad-work-piece contact. Recessed surface micro texture structuresor surface voids 23, as described in this said invention, act to holdthe polishing fluid at the surface of the pad.

[0043] The shape and texture of the said micro-pore-structure 26 willvary with the method of manufacture from spherical to channels of pores.

[0044] Macro texturing is often desirable for a polishing pad toincrease the flow of material across he pad and to the surface of thework-piece. FIG. 12 shows and example of macro grooving showing grooved32 and un-grooved areas 31. These grooves can be linear or circular orany shape. FIG. 13 gives a conceptual example of a circular polishingpad with circular grooves 31. In reality, there would be many moregrooves than that shown in FIG. 13.

[0045] Methods for material-liberation for the said PDL, PDL-2 and PDL-3phases include but are not limited to:

[0046] a) Chemical dissolution into the usually aqueous media of thepolishing solution, pad or work-piece cleaning or rinsing solution orpad conditioning solution. This action may be enhanced or controlled bythe addition or subtraction of acids, bases, or dilute solvents into orfrom the said above solutions.

[0047] b) Pretreated chemical dissolution processes into a solvent typebath, including but not limited to a pretreatment operations during themanufacturer of the polishing pad at a set amount of pore depthcreation.

[0048] c) Chemical reactions with a contacting liquid or gas, whichresults in by-products which are liberated from the pad. This method maybe enhanced by placing reactive species in either the polishing, padconditioning, work-piece rinsing or pad rinsing fluids.

[0049] d) Phase changes due to exposure to atmospheric pressure,increased temperatures, induced shear, or induced strain due polishing,pad conditioning processes, or similar shear and strain inducingprocesses.

[0050] e) Significantly higher physical wear rates between PDL 12, PDL-222 and PDL-3 35 and PPP material 11, during polishing or padconditioning type processes.

[0051] f) Surface degradation, decomposition, reaction, dissolution,increase mobility or other means of surface liberation due to an appliedsurface energy flux, including but not limited to light, acoustic orsonic energy, vibrations or thermal energy.

[0052] g) Deformation and increased mobility due to increases in thesurrounding temperature or by means of induced pressures and shearrates.

[0053] h) Swelling or partial dissolution of material in concert withmeans of surface abrasion or agitation.

[0054] i) Combinations of the above.

[0055] Examples of methods and materials include but are not limited to:

[0056] Method (a) chemical dissolution:

[0057] Using materials and methods for material liberation for all orportions of the said PDL 12, PDL-2 22 or PDL-3 35 phases, which include,but are not limited to, the following systems of materials and fluids:

[0058] i. At least a partial quantity of water soluble polymers such asPolyacrylic acids, hydroxypropylcellulose, or Polyethylene oxide (assold by Union Carbide of Danbury Conn. as Polyoxy products WSRN-750 andothers), and blends of these types of polymers such that the overallmixture of materials is soluble in a desired polishing, rinsing,conditioning or other fluid. For example WSRN-750 PDL 12 dissolves inwater, when used with a water rinsing fluid.

[0059] ii. Water-soluble solid salts or crystals such as sugars, solublesolid acid, potassium nitrite or for example solid oxalic or citric acidin water.

[0060] iii. Inorganic particles such as CaCO₃ in dilute acid, Ca (NO₃)₂in water, CaO in acid, ammonium nitrate in water, K₂CO₃ in water,Ar(SO₄)₂ in water or potassium acetate in alkaline conditions, asexamples.

[0061] iv. Inorganic-organic complexes such as partially coagulated orreacted silica, ceria or other inorganic particles or molecular levelspecies of inorganic materials (ceria, silica) with polyethylene oxidepolymers, as an example.

[0062] In this method, the PDL 12 examples listed above are fashionedinto a polishing pad, as part of this invention. The said polishing padis then contacted with the said example fluids discussed in method (a).Some portion of the PDL 12 is hence dissolved into the said fluidsleaving the said desired surface voids 14 forming the desired surfacemicro-texture.

[0063] Methods (b) chemical reaction: Some portion of PDL 12, PDL-2 22,or PDL-3 36 are made from the following system of materials and fluids,but not limited to:

[0064] i. Lithium metal particle reacting with water.

[0065] ii. Sulfur particles with hydrogen peroxide solutions.

[0066] This method works in a similar manner as discussed in method (a),with the added distinction that rather than some portion of the PDL 12dissolving, the said PDL chemically reacts with the contacting fluid,hence liberating a reaction by-product from the surface of the saidpolishing pad forming said desired void 14, for example.

[0067] Methods (c) of phase changes: Using materials and methods formaterial liberation for all or portions of the said PDL 12, PDL-2 22 orPDL-3 35 phases, which include, but are not limited to, the followingsystems of materials and fluids:

[0068] i. Low melting temperatures materials, materials sensitive tophase changes caused by pressure changes, increased temperatures,induced shear or strain. For example, elastomeric polymers will act assolids under compression or impact, yet will flow as a liquid, whenintroduced to some flow conditions.

[0069] Methods (d) of wear rates: Using materials and methods formaterials liberation for all or portions of the said PDL 12, PDL-2 22 orPDL-3 35 phases, which have a significantly higher physical wear ratethan the PPP material 11, including but not limited to:

[0070] i. Matrix polymers such as Texin 250 Thermoplastic urethane (11)as sold by Bayer Incorporated of Pittsburgh Pa., combined with PDL 22materials with higher physical wear rates such as polypropylene, forexample. The wear is induced by the act of polishing or pad conditions(where friction and mechanical wear are introduced to the pad surface).

[0071] Examples of the polymeric-particle phase (PPP) material 11include but are not limited to urethane polymer, an acrylated urethane,and acrylated epoxy and ethylenically unsaturated organic compoundhaving a carboxyl, benzyl or amide functionality, an aminoplastderivative having a pendant unsaturated carbonyl group, and isocyanratederivative having at least one pendant acrylate group, a vinyl ether, apolyacrylamide, an ethylene ester copolymer or an acid derivativethereof, a polyvinyl alcohol, a polymethyl methacrylate, an ABS, apolysulfone, a polyamide, a polycarbonate, a polyvinyl chloride, anepoxy, a copolymer of the above or a combination thereof.

[0072] The PPP material 11 should have the following bulk or surfacephysical properties:

[0073] Hydrophilic intrinsically or at least after a diamond padconditioning, or other method, has been used to form surfacemicro-texture on the scale of 1-5 microns.

[0074] A density of grater than 0.5 g/cm3

[0075] A critical surface tension of greater than 33.5 milliNewtons/m

[0076] A tensile modulus of 0.02 to 5 gigapascals

[0077] A ratio of tensile modulus at 30 C. to tensile modulus at 60 C.of 1.0 to 2.5

[0078] A shore D hardness of 25 to 90.

[0079] A yield stress of 300-6000 psi

[0080] A tensile strength of 1000 to 15000 psi

[0081] An elongation to break less than or equal to 500%

[0082] Methods of Manufacturer

[0083] Example of proposed manufacturing methods are shown below. By nomeans are the examples limiting the materials nor methods available formaking the above described invention.

EXAMPLE 1

[0084] Preferred Embodiment 1, PDL

[0085] Texin 250 Thermal plastic urethane from Bayer Incorporated ofPittsburgh Pa. (PPP 11) is cold milled to an initial the size range lessthan 250 microns in average diameter. This material can then be madeinto a sintered polymer particle matrix (PPM) using method know in theart, as described in U.S. Pat. No. 6,017,265 example 1.

[0086] This urethane material has now formed a PPM. This matrix pad isnow impregnated with Polyoxy® WSRN-750 from Union Carbide of DanburyConn. Impregnation to fill the voids in the interstitials and otherlocations in the PPM can take place by several methods. In this example,the WSRN-750 is completed dissolved in water at elevated temperaturesuntil such a concentration to form a past like material. This materialis then pressed into the pores of the PPM using a Teflon squeegee. Thepaste is added until paste material begins to evolve from the backsideof the polishing pad. The pad is then dried in an oven for 10 hours at90 C. The pad is then cooled to room temperature for 2-10 hours. Aftercooling, paste is re-applied to the pad. Excess paste is removed withthe squeegee. The pad is baked again for 10 hours at 90 C. and thencooled for 2 hours before being fashioned into a polishing pad.

[0087] The resulting pad is then cut into the desired shape.Macro-grooving 32 is done using metallic cutting tools such as lathes orcutting saws. The pad is then laminated with adhesive.

EXAMPLE 2

[0088] Second embodiment, PDL-2

[0089] Using a high melt temperature thermoplastic from the listcompiled for the PPP material 11, a sintered pad matrix is formed, wherethe material chosen has a melting and softening temperature in excess of220 C. The formed PPM, by methods discussing the in current art, is madeflat by a variety of methods including molding and hot rolling.

[0090] Texin 250 Thermal plastic urethane from Bayer Incorporated ofPittsburgh Pa. (polymeric matrix phase 11), is mixed with 25% Polyoxy®WSRN-10 and 25% WSRN-750 by volume, both from Union Carbide of DanburyConn. (PDL-2 22). The said PDL 22 is initially the size range less than250 microns in diameter. These materials are combined in a commerciallyavailable heated mixer at a temperature of 190 C. The said Texin 250 andWSRN-10 are introduced into the mixer in a manner known by those skilledin the art to achieve a substantially melted and well-mixed material, tothe scale of less than 10 microns.

[0091] The above-mentioned PPM material is then fed trough a flatextruder die of dimensions not more than 50 microns wider than the widthof the PPM. The melt formed above is held in the extruder die at apressure sufficient enough to force the melt material into theinterstitial pore structure of the said PPM (in excess of 10 PSIG). Asthe PPM roll is pulled from the extruder, the said melt is forced intothe pore structure of the PPM as described earlier in this invention.

[0092] The extruded pad can then be ed right onto a desired substratesuch as Mylar (from Dupont), Suba-4 (from Rodel Inc.) or commerciallyavailable rubber or foam sheets. The extruded sheets can bemacro-grooved 32 using metallic cutting tools, such as lathes withcutting die or saw cutting tools. The pad is then cut into the desiredshape and laminated with adhesive.

EXAMPLE 3

[0093] PDL-3

[0094] Texin 250 Thermal plastic urethane from Bayer Incorporated ofPittsburgh Pa. (polymeric matrix phase 11), is mixed with 25% Polyoxy®WSRN-10 and 15% WSRN-750 by volume, both from Union Carbide of DanburyConn. (PDL-3 35). The said PDL-3 35 is initially the size range lessthan 250 microns in diameter. These materials are combined in acommercially available heated mixer at a temperature of 190 C. The saidTexin 250, WSRN-10, and WSRN-750 are introduced into the mixer in amanner known by those skilled in the art to achieve a substantiallymelted and well-mixed material, to the scale of less than 10 microns.

[0095] Using a high melt temperature thermoplastic from the listcompiled for the PPP material, PPP-material of diameter of less than 250microns are added to the above melt, slowly so as to fully dispensethese particles. The PPP-material particles are added until a volumepercentage of 40% is reached. This melt-suspension is then added to acommercial extruder at a temperature around 190 C. This melt-suspensionis then extruded out through a flat grading (approximately 30 incheswide, 80 mils high and with a groove-making grating 25 mils deep, with80 mil top areas 31 and 30 mil down areas 32.

[0096] The extruded film can fed right onto a desired substrate such asMylar (from Dupont), Suba-4 (from Rodel Inc.) or commercially availablerubber or foam sheets. The extruded sheets can be case with continuousgrooves by use of a grooved die. The final pads can then beheat-pressed, mechanically cut and grooved into the desired macro-shapeand size by suing metallic molds with the desired pad structure cut intothe mold. In this example a concentric groove design is pressed into thepad by heating the mold to an effective temperature. The pad is then cutinto the desired shape and laminated with adhesive.

[0097] Operation

[0098] Use of a polishing pad is a well-documented method for a varietyof polisher types, and is easily conducted by one skilled in the art.Briefly, the operation of this polish pad is reviewed. The starting padreferenced in this section is that shown in FIG. 1 100 and made byexample 1.

[0099] The finished pad is first attached to the working surface of apolisher by a desired method of adhesion, usually using apressure-sensitive-adhesive (PSA) and applied pressure along the topsurface of the pad 600 to fasten the pad via the PSA to the workingsurface of the polisher. After the pad is attached, the pad surface mustbe treated to enact the appropriate method of creating surface pores 14.Using the preferred embodiment of a the polishing pad (examples 1). a 5minute conditioning run is employed while flowing a generous amount ofroom temperature water. The conditioning method uses a standardconditioning disk as the work-piece on the polishers conditioning arm atapproximately 12 lbf on a 4-inch conditioner using a sweeping motionwith the table rotating at a rate of usually over 10 RPM. This standardconditioning disk is readily commercially available. In standard diamondconditioners, the sharp tip of the diamond projects normal to the planeof the conditioning disk. During this initial break-in, the conditioningdisk flattens the pad surface, cuts grooves in the PPP-materials 11 andremoves a thin layer of the said pad. This condition operation bringsthe pad to a condition that can be maintained as steady state during theoperation of polishing several substrates. The surface of the polishingpad 100 is now exposed to the flow of water and in doing so starts thedissolution of these materials. After sufficient time, the PDL 12materials dissolve and are carried away by the wafer flow rate inconjunction with the pad conditioning, creating the desire porestructure 14. Length of this operation can be reduced by any method thatenhances solubility of the PDL—the use of pressurized wafer deliverysystems and high water temperatures as examples. This break-in procedurecan be modified for deeper pore structure 14 by reducing the cut rate ofthe diamond pad conditioner, increasing the rinsing time and using amore easily soluble PDL material 12. At the end of the initial break-in,the desired surface pore depth 13 and pore 14 structures of the saidinvention 200 polishing pad have been created.

[0100] After this initial break-in, wafers, or the like, are loaded onthe polisher where a polishing arm or other apparatus holds the wafer,or the like, in contact with the polishing pad in the presence of slurryor other polishing fluid. These slurries or fluids usually flow acrossthe surface of the pad and are then moved between the wafer and the padby virtue of the motion of the pad with respect to the wafer. Thedesired polishing of the wafer or work-piece usually takes place byvirtue of the contact of the slurry or fluid with the wafer orwork-piece in the presence of the polishing pad, in motion, at elevatedcontacting pressures.

[0101] Conclusions, Ramifications and Scope

[0102] The invention teaches a novel structure, means of constructingand operation for a polishing pad. This invention enhances the designand operation of polishing pads that offer an interconnected porestructure, such as that found on sintered-materials polishing pads. Theadvantages of this invention include:

[0103] 1. The polishing pad can incorporate a slowly dissolving PDL,PDL-2 or PDL-3 phases, which can act as a self cleaning method for thepad, thus lowering the critically of the pad conditioning process, forsome applications.

[0104] 2. The top surface polishing ore depth can be substantiallycontrolled by the pad manufacturing method, PDL materials and the padoperation process.

[0105] 3. The methods of pad manufacturing can be substantiallysimplified over case and skive methods. Less expensive and moremanufacturable methods such as extruding or injection molding aredifficult to use in pad manufacturing because they operate at extremeconditions and tend to yield smooth polymer surfaces (microscopically).This invention allows for these methods to be employed and still have aviable route for creating surface texture.

[0106] 4. The chemistry with in the PDL, PDL-2, or PDL-3 phases may aidin pad conditioning, wafer cleaning or work-piece polishing performance.

[0107] 5. The formed pad, as compared to the current art shown in FIG.5, can be considerably stiffer, due to the added stiffness and rigidityof the fill material over that of air or the polishing fluids.

[0108] Although the description above contains many specificities, theseshould not be construed as limiting the scope of the invention butmerely providing illustrations of some of the presently preferredembodiments of this invention.

1. A polishing pad comprising a mixture of at least two material typeswhere, a) a first material participates of a contiguous collection ofpolymeric like particles to form the body of polymeric like structure,and b) a second material acts to fill some portion of the void spacesbetween the polymeric like particles.
 2. A polishing pad comprising amixture of at least two material types where, a. a first materialparticipates of a contiguous collection of polymeric like particles toform the body of polymeric like structure, and b. a second material actsto fill some portion of the void spaces created, and c. some portion ofthe second material type is liberated from the surface of the saidpolishing pad resulting in the creation of surface texture.
 3. Apolishing pad in accordance with claims 1 or 2 wherein said methods ofmaterial liberation include: contacting the said polishing pads with afluid, which acts to dissolve the said portion of the said secondmaterial, either as the sole method of material liberation or combinedwith any number of other means of surface material liberation.
 4. Apolishing pad in accordance to claim 3 where the said fluid is water ineither an acidic, neutral or basic pH range and said second material iscomprised of a host of soluble materials which includes but is notlimited to, a. polymeric materials including Polyacrylic acid,Polyethylene oxide, b. inorganic materials including CaO, CaCO₃,Ca(NO₃)₃, KCO₃, Zr(SO₄)₂, c. salts or crystals including sugars anddried acids and, d. physical and molecular level combinations of theabove either as the sole method of material liberation or combined withany number of other means of surface material liberation.
 5. A polishingpad in accordance with claim 1 or 2 wherein said methods of materialliberation include, contracting the said polishing pad with a substancewhich chemically reacts with the said second material and forms reactionbyproducts which become liberated from the surface of the said polishingpad, either as the sole method of material liberation or combined withany number of other means of surface material liberation.
 6. A polishingpad in accordance with claim 1 or 2 wherein said methods of materialliberation include, exposing the said polishing pad with a environmentwhich lends the second material to undergo a phase transformation whichresults in a volatile or otherwise mobile condition which facilitatesthe liberation of the said second material, either as the sole method ofmaterial liberation or combined with any number of other means ofsurface material liberation.
 7. A polishing pad in accordance withclaims 1 or 2 wherein said methods of material liberation include:exposing the said polishing pad with a environment which lends thesecond material to substantially higher rate of physical wear whencompared to the said polymer like particle material 11, either as thesole method of material liberation or combined with any number of othermeans of surface material liberation.
 8. A polishing pad in accordancewith claim 1 wherein said methods of material liberation include:exposing the said polishing pad with a environment which lends he saidsecond material to undergo a phase transformation which results in avolatile or otherwise mobile condition which facilitates the liberationof the said second material, either as the sole method of materialoperation or combined with any other number of means of surface materialliberation.
 9. A polishing pad in accordance with claims 1 or 2 whereinsaid methods of material liberation includes but is not limited toexposing the said polishing pad to an environment which induces the saidsecond material to physically wear at a substantially higher rate whencompared to the remainder of the polishing pad, creating surfacetopography, either as the sole method of material liberation or combinedwith any other number of means of surface material liberation.
 10. Apolishing pad in accordance with claims 1 or 2 wherein said methods ofmaterial liberation includes but is not limited to exposing the saidpolishing pad to temperatures, pressures, shear rates, abrasion orsurfaced agitation where the said second phase undergoes a deformation,decomposition, reaction, or increased mobility of said second materialwhen compared to he remainder of the polishing pad material, creatingsurface topography, either as the sole method of material liberation orcombined with any other number of means of surface material liberation.11. A polishing pad in accordance with claims 1 or 2 wherein saidmethods of material liberation includes but is not limited to exposingthe said polishing pad to an applied surface energy flux including butnot limited to light, acoustic or sonic energy, vibrations or thermalenergy resulting in either surface degradation, decomposition, reaction,dissolution, increase mobility, combination or other means of surfaceliberation of said second material when compared to the remainder of thepolishing pad, creating surface topography, either as the sole method ofmaterial liberation or combined with any other number of means ofsurface material liberation.
 12. A polishing pad in accordance to claims1 or 2 where the recess 13 of the said second material is greater than 1microns and less than 10,000 microns.
 13. A polishing pad in accordanceto claims 1 or 2 where the recess 13 of the said second material isgreater than 50 microns and less than 500 microns.
 14. A polishing padin accordance to claims 1 or 2 where the said pore depth or said surfacetexture of the said polishing pad is controlled by the depth that thesaid second material has been liberated from the said polishing padsurface.
 15. A polishing pad in accordance to claim 1 or 2 where thesaid polymeric like particle material 11 has a hydrophilic surface, atleast after pad conditioning or creation of surface texture and iscomposed of a density of greater than 0.5 g/cm3, a critical surfacetension of greater than 33.5 milliNewtons/m, a tensile modulus of 0.02to 5 gigapascals, a ratio of tensile modulus at 30 C. to tensile modulusat 60 C. of 1.0 to 2.5, a shore-D hardness of 25 to 90, a yield stressof 300-600 psi, a tensile strength of 1000 to 15000 psi, an elongationto break less than or equal to 500%.
 16. A polishing pad in accordancewith claims 1 or 2 where the liberated material either provides: gasbubbles for wafer release and cleaning, lubricants for reduced friction,active polishing ingredients, self cleaning or pores, secondaryreactions to eliminate undesired polishing by-products, or bufferingproperties.
 17. A polishing pad where multiple layers of the polishingpad materials are positioned one or the other and assembled togetherwith a connecting material used to fill spaces between these pad layers.18. A polishing pad in accordance with claims 1 or 2 and claim 17 wherethe polishing pad materials are the said first material and the saidconnecting materials are the said second material.
 19. A polishing padin accordance with claim 17 or 18 where the said multiple layers can beexposed with the use of an extensive liberation process, by any of anumber of means, to allow for the expose of an underlying layer belowthe surface layer, with the benefit of removing this top layer to exposethe lower layer in a manner where fresh pad surfaces can be exposed forpolishing use in a repeating fashion, dictated by the number ofremaining pad layers and the polishing application.
 20. A polishing padin accordance with claim 19 where the said pad contact polishing surfacecan be removed to expose a lower level as a fresh polishing surfacewithout removing the pad from the polisher to facilitate applicationneeds typically addresses by changing the polishing pad, including butnot limited to raised defects levels due to paid degradation andcontamination, process changes between incompatible processes, andundesired thickness profiles induced into the top surface pad wear.